More Findings, More Questions About Value Of Mammograms

There's new evidence out today that's raising questions about whether women in their 40's and 50's should routinely undergo mammography to detect breast cancer. A new analysis of a big Canadian study found no evidence that regular mammograms save lives. The study even suggests that for many women, regular breast X-rays may do more harm than good.

NPR's Rob Stein joins us now to talk about this report. It appears in the British medical journal BMJ.

And, Rob, let's start with the backdrop to this, because there has been a long-running debate about the effectiveness of mammograms.

ROB STEIN, BYLINE: Yeah. That's right, Melissa. The debate over mammography for breast cancer has been raging for years and it's probably the most intense, emotional debate in women's health. And there's a good reason for that. I mean, for years women had been told that they should start getting regular mammograms once they turn 40. And it's a really important thing they can do to protect themselves from dying from breast cancer, that it will catch breast cancer at its earliest, most treatable stages.

But in recent years, experts have started to question that, especially for women younger women, women in their 40's. They say the evidence has been mounting that routine mammograms for those younger women doesn't really cut the death toll from breast cancer. And it could end up doing more harm than good. And here's how. When women get a mammogram, you know, they often get something that looks like it might be a problem. They get called back for another mammogram or for a biopsy. And it turns out to be nothing.

So that creates a lot of anxiety and a lot of stress. And, even when they find something, they end up getting radiation or chemotherapy which can be toxic; or surgery, including mastectomies, for a thing that may never end up being life-threatening.

BLOCK: And this new study that were talking about seems to offer yet more evidence to support that idea, that we are using mammograms - that women are getting mammograms too much. What did the study find?

STEIN: Yeah, this is a very large study that's been going on in Canada for decades. Researchers have been following nearly 90,000 women who either got a mammogram in their 40's or 50's, or got a physical breast exam and no mammogram. These researchers had previously reported that there was no reduction in deaths among the women getting mammograms. Now they're updating those findings after following these women for 25 years.

And once again they find the same thing: Women who got mammograms were no less likely to die from breast cancer than the women who didn't. And for the first time they're able to calculate the harms. You know, how many women ended up getting treated for things they really did need to get treated for? And they estimate that as many as one in five and perhaps one in three women who were diagnosed with a mammogram get treated unnecessarily.

BLOCK: When you say unnecessarily, again, it's because they're getting treated for cancerous growth that would not have been life-threatening.

STEIN: That's right. There are some very small tumors or pre-cancers that would never progress. They'd never even know that they had it and certainly would never become life-threatening.

BLOCK: Rob, this has been a really confusing issue for a lot of women. Does this new study settle the debate or is the confusion going to be going on in every doctor's office around the country?

STEIN: Yeah, unfortunately I don't think this going to settle this anytime soon. There's still a huge amount of debate about this. I spent the day talking to a lot of experts, the folks at the American College of Radiology, American Cancer Society. And they, you know, dismissed these findings. They say there are huge flaws with the study, that there is still the case, for example, they don't think the mammography that was used in these women was very good.

But a lot of other people support these findings and think they are the reason why we should really be thinking twice about mammograms. So this isn't going away anytime soon, unfortunately.